1. Field of Invention
This invention relates generally to vinyl chloride plasticizers and more particularly to novel stain resistant plasticizers.
2. Description of the Prior Art
Many polymeric materials, e.g., poly (vinyl chloride), cellulosics, etc., are of a relatively hard and brittle nature. To improve softness and flexibility so that the resulting product is usable in a wide variety of applications, it is necessary to add a plasticizing agent to the polymer. The basic attributes of a good plasticizer are:
(1) compatibility with the polymer or resin it is to plasticize; PA1 (2) capability of imparting desired processability and softness, etc.; PA1 (3) thermal stability under the conditions of processing and subsequent aging; and PA1 (4) permanence to loss, particularly through volatilization, but also through solvent extraction, migration or exudation.
Compatibility is normally defined as the ability of the plasticizer to produce a clear film and to remain more or less homogeneously dispersed throughout the resin composition, particularly on aging. Permanence refers to the tendency of the plasticizer to resist loss through volatilization, chemical breakdown, extraction by water, soapy water, or organic solvents, migration and exudation. Other important attributes of a plasticizer are efficiency, i.e., the amount of plasticizer required to impart desired properties (depending on relative costs and specific gravities of the plasticizer and resin, high efficiency can result in reduced or increased volume costs of the plasticized resin composition), ability to impart low temperature flexibility to a resin, ability to allow ease of processing to the resin system, i.e., flows and molds or extrudes readily and the like.
Providing improved stain resistant surfaces is a highly important objective of the flooring and wall covering industries in vinyl resin end-uses such as protective coverings for surfaces which are usually designed to decorate and enhance the appearance of the area. In many uses, these protective surface coverings are exposed to wear and abrasion and in addition are exposed to action by other materials which tend to discolor or stain the composition thereby materially reducing the decorative appearance of the covering. The problem of staining is not limited to but is especially serious in poly (vinyl chloride) covering compositions used on walls and floors and other areas where there is frequent exposure to and contact with materials which tend to stain and discolor.
However, due to the wide variety of possible stainants with which, for example, vinyl sheet flooring can be expected to come into contact over its useful life, stain resistance is a highly complex problem which is only incompletely understood. The determination of stain resistance of plasticized poly (vinyl chloride), and the complex problems associated therewith, are discussed at some length in J. K. Sears and J. R. Darby, The Technology of Plasticizers, pages 555-580 (1982).
Therefore, a stain resistant plasticizer must satisfy the usual basic plasticizer attributes and, in addition, impart the desired stain resistant properties in the plasticized resins.
Prior art plasticizers which have been found to impart improved stain resistant properties to plasticized vinyl chloride compositions include those disclosed in U.S. Pat. Nos. 3,158,585 and 3,160,599. The stain resistant plasticizers of U.S. Pat. No. 3,158,585 comprise esters of phthalic acid, in which the alcohol moieties thereof are selected from the group consisting of tetrahydropyran-2-methyl groups, alkoxyalkylene groups having 3 to 8 carbon atoms, and lower alkyl groups having from 1 to 5 carbon atoms. The stain resistant plasticizers of U.S. Pat. No. 3,160,569 comprise the monoisobutyrate monobenzoate ester of 2,2,4-trimethyl-pentane-1,3-diol having the structural formula (I): ##STR1## wherein R.sup.1 and R.sup.2 together represent the radicals ##STR2##
A. V. Bailey, et. al., J. Amer. Oil Chem. Soc., vol. 53, 176-178 (1976) investigated the use as PVC plasticizers of certain mixed esters of three diols (ethylene glycol, diethylene glycol and 2-butene-1,4-diol) wherein one of the ester moieties was benzoate. Esters containing two aroyl groups or benzoyl and a short branched-chain alkanoyl group (trimethylacetate) were found to be compatible plasticizers for PVC resin. However, esters containing one benzoyl group and a longer chain alkanoyl group gave mixed results; with the C.sub.29 triester (benzoyloxyethyl 12-acetoxyoleate) and C.sub.21 diester (benzoyloxyethyl laurate) compounds being found to be compatible, whereas the C.sub.27 diester (benzoyloxyethyl oleate) and C.sub.25 diester (benzoyloxyethyl palmitate) compounds were not. (Related to the A. V. Bailey et. al., article are U.S. Pat. Nos. 4,024,164; 4,074,058 and 4,107,192.)
E. J. Wickson, et. al., Soc. Plastic Eng. Preprint, Annual Technical Conference, pp. 238-242 (1969) compares certain PVC plasticizer performance properties of ethylene glycol diesters in which one ester group is derived from neo-decanoic acid and neotridecanoic acid and in which the second ester group is derived from a dibasic acid selected from the group consisting of adipic, azelaic and phthalic acids.
U.S. Pat. No. 2,454,274 relates to the manufacture of certain mixed aliphatic aromatic esters of glycols such as ethylene glycol acetate benzoate and to their use as plasticizers for organic esters and ethers of cellulose.
U.S. Pat. Nos. 2,700,656 and 2,766,266 relate to plasticized polyvinyl chloride compositions containing diesters of substituted 1,5-pentene diols in which one ester in the group is derived from an aromatic acid and the second ester group is derived from certain mono-carboxylic aliphatic acids. Mono-carboxylic aliphatic acids containing from 8 to 12 carbon atoms, with caprylic, pelargonic, capric, undecylic, lauric, 2-ethyl-hexanoic acids are indicated as suitable.
U.S. Pat. No. 3,072,591 relates to plasticized vinyl resins in which the plasticizer is one or more aromatic-aliphatic carboxylic acid mixed esters of a polymethylolalkane containing at least three methylol groups, wherein one mole of an aromatic acid, and the remaining methylol groups are esterified with one or more saturated aliphatic acids having an average carbon content of not less than 6 carbon atoms, with individual aliphatic acids ranging from 6 to 18 carbon atoms, and mixtures of aliphatic acids ranging from 4 to 18 carbon atoms.
U.S. Pat. No. 3,341,574 relates to synthetic high temperature lubricant compositions comprising of carboxylic acid esters having a carboxylic group bonded to a quaternary carbon atom (the alpha carbon), with a polyol having a quaternary carbon atom bonded to 2 to 3 methylol groups. The esters include neoalkanoic acid esters, with suitable neoalkanoic acids being indicated as including 2,2-dimethylalkanoic acids having chain lengths of from 4 to 13 carbons such as neodecanoic acid, neotridecanoic acid, 2,2,4,4-tetramethylpentanoic acid, 2-methyl-2-ethyl caproic acid, neo-nonanoic acid and neo-heptanoic acid, which is preferred. Suitable polyols include trimethylolpropane, trimethylolethane, 2,2,4-trimethyl 1,3-pentanediol and 2-butyl, 2-ethyl propanediol. However, no plasticizer use of these lubricants is disclosed or suggested.
U.S. Pat. No. 3,433,661 discloses certain stain resistant plasticizers which are complex mono-esters prepared from aromatic hydrocarbons, formaldehyde and certain monocarboxylic acids.
U.S. Pat. No. 3,562,300 relates to liquid neoalkylpolyol esters of mixtures of neo- and straight or branched-chain alkanoic esters, which are disclosed to be useful as lubricants or plasticizers, and which are prepared by esterifying (1) a neo-alkyl polyol of up to 10 or 12 or more carbon atoms and 2 to 6 hydroxyl groups with (2) a straight chain alkanoic carboxylic acid having from 4 to 12 carbon atoms or branched chain alkanoic acids of 4 to 12 carbon atoms other than neo acids, and (3) a neo alkanoic acid having 5 to 20 carbon atoms. The patentee's esters are prepared by a multi-step procedure and are said to provide improved properties over known lubricants including neoalkylpolyol esters of straight chain fatty acids (e.g., pentaerythritol tetracaproate); esters derived from neoalkylpolyols and branched-chain fatty acids (e.g., pentaerythritol tetrapivalate); di-ethylhexyl sebacate; esters of neoalkyl fatty acids and neoalkyl polyols of 3 to 5 hydroxyl groups; and esters prepared from neopentylpolyols and mixtures of neo- and straight-chain acids (e.g., pentaerythritol esters of mixtures of neoheptanoic and n-valeric acids containing less than 50 mol.% n-valeric groups) using the therein described "conventional" one-step procedure.
U.S. Pat. No. 3,652,610 is directed to plasticizers prepared by the reaction of a hindered acid glycol monoester and di- or tri-basic acids or anhydrides. Illustrative of the monoester reactant are the neo-acid esters of C.sub.2 -C.sub.15 alkanols, in which the neo-acid moiety can be derived from trimethylacetic acid; alpha, alpha-dimethyl cyclohexylacetic acid; alpha, alpha-dimethyl phenylacetic acid; alpha, alpha-dimethyl pentanoic acid and the like.
Japanense Patent Publication 77/101,253 discloses plasticizers comprising polyalkylene glycol diesters which have 1 to 14 ether bonds and which are derived from 2 to 6 carbon atom alkylene glycols, and have one benzoic acid ester group and a second ester group derived from straight chain, saturated fatty acids of 8 to 22 carbons, or from branched chain, saturated fatty acids of 8 to 22 carbons which are substituted on the alpha-carbon by a 1 to 10 carbon side chain.